On Wed, 2008-11-05 at 11:33 -0600, Anthony Liguori wrote: > Hollis Blanchard wrote: > > On Wed, 2008-11-05 at 11:25 -0600, Anthony Liguori wrote: > > > >> I think we should just have a VIRTIO_PFN_SHIFT define that is > >> architecture specific. > >> > >> On x86, it'll be 4k. You can make it whatever you want for PPC. > >> Fixing all architectures to be 4k is going to suck for architectures > >> with < 4k pages. > >> > > > > So we're now in agreement that it should be hardcoded. I don't see much > > value in making the actual value arch-specific, but either way it will > > solve (at least part of, and maybe all of) my problem. Rusty? > > > > When you balloon pages, you need to pass something that points to the > beginning of a page boundary. If your page size is 2k, then if you are > only able to pass 4k addresses, you can't below any page that happens to > not be 4k aligned. > > If you were going to make it common across all architectures, you would > have to make it the smallest possible page size and that would break x86 > backwards compatibility. OK, makes sense to me. -- Hollis Blanchard IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
